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United States Patent |
5,197,559
|
Garin, III
,   et al.
|
March 30, 1993
|
Foldable wheelchair with optional power or manual drive
Abstract
An economical light weight foldable wheelchair is selectively operable in a
motorized, attendant or occupant driven self-propelled mode of operation.
The wheelchair includes two opposed side frames that are foldable to a
laterally more compact condition, a motor drive assembly and a foldable
energy supply system support assembly. The energy supply system support
assembly slidably receives two battery units with convenient front access
and automatic electrical connection. Storage under the seat assures a
center of gravity well ahead of the rear wheels. The motor drive system
includes a releasable wheel drive assembly that supports two large rear
wheels with a center of rotation behind, under or in front of the back
support of the seat. Manual drive rings are mounted on the outside of the
rear wheels and the occupant can easily reach a hub mounted toggle handle
for the wheel drive assembly to control engagement of the rear wheels with
the drive motors. An occupant may thus use the motor drive assembly or
idsengage the drive motors and manually self-propel the wheelchair using
the manual drive rings.
Inventors:
|
Garin, III; Paul V. (Clovis, CA);
Lusk; Donald E. (Fresno, CA)
|
Assignee:
|
Fortress Life-Style, Inc. (CA)
|
Appl. No.:
|
579156 |
Filed:
|
September 4, 1990 |
Current U.S. Class: |
180/65.1; 180/68.5; 180/907; 280/250.1; D11/131; D12/131 |
Intern'l Class: |
B60K 001/00 |
Field of Search: |
280/250.1
180/68.5,65.1,65.2,907
105/51
|
References Cited
U.S. Patent Documents
265703 | Apr., 1953 | Goeller | 180/13.
|
1165784 | Dec., 1915 | Klingelsmith | 180/65.
|
2798565 | Jul., 1957 | Rosenthal et al. | 180/6.
|
3107105 | Oct., 1963 | Heriford | 280/42.
|
3437164 | Apr., 1969 | Rabjohn | 180/68.
|
3497027 | Feb., 1970 | Wild | 180/65.
|
3613813 | Oct., 1971 | Biddle | 180/6.
|
3708028 | Jan., 1973 | Hafer | 180/65.
|
3889773 | Jun., 1975 | Chant | 180/65.
|
4199036 | Apr., 1980 | Wereb | 180/6.
|
4323133 | Apr., 1982 | Williams | 180/65.
|
4436320 | Mar., 1984 | Brudermann et al. | 280/250.
|
4512613 | Apr., 1985 | Nassiri | 301/1.
|
4671524 | Jun., 1987 | Haubenwallner | 280/212.
|
4756978 | Jul., 1988 | Nitcher et al. | 429/1.
|
Foreign Patent Documents |
2315390 | Oct., 1973 | DE | 180/68.
|
2134056 | Aug., 1984 | GB | 180/907.
|
2192161 | Jan., 1988 | GB | 180/65.
|
Other References
A-BEC Product Literature.
Falcon Rehabilitation Product Literature.
Folio Product Literature.
Kempf Product Literature.
Willhelm Meyer GmbH & Co. Product Literature.
Boden Rehab Ad Product Literature.
Everest & Jennings Product Literature.
Invicar Product Literature.
Fauteuils Electroniques Dupont Product Literature.
Global Research Limited Product Literature.
Twenty-First (21st) Century Scientific Inc. Product Literature.
Inter-med Incorporated Product Literature.
MK Battery Product Literature.
|
Primary Examiner: Culbreth; Eric D.
Claims
What is claimed is:
1. A foldable motor driven wheelchair comprising:
a first and a second side frame, parallel to each other and extending in
vertical and longitudinal directions;
a foldable seat carried by and extending transversely between the side
frames;
a supporting structure connecting the side frames for motion between an
unfolded position in which the side frames are spaced sufficiently apart
to accommodate an occupant with the seat unfolded thereunder and a folded
position in which the side frames are relatively closer together in
side-by-side relation with the seat folded therebetween;
a motor controller supported on at least one of said side frames;
at least one electric motor supported by at least one of the side frames
and electrically coupled to the motor controller;
a foldable baseplate pivotably connected to and extending between the
wheelchair side frames wherein said foldable baseplate includes a first
plate and a second plate movably connected to each other by a hinge
assembly having a pivot point and at least one first hinge member and at
least one second hinge member extending outward from said pivot plant,
wherein said at least one first hinge member is attached to said first
plate and said at least one second hinge member is attached to said second
plate;
means of mechanically affixing said removable battery unit to said foldable
baseplate;
means attached to said foldable baseplate of electrically connecting said
removable battery unit to said motor controller;
wherein said first plate, having a first and a second longitudinal edge,
said first longitudinal edge terminating at said first side frame and said
second longitudinal edge terminating at a location between said hinge
assembly and said second side frame and said second plate, having a first
and a second longitudinal edge, said first longitudinal edge terminating
at said second side frame and said second longitudinal edge terminating at
a location between said hinge assembly and said second said frame; and
wherein, when the wheelchair is in the unfolded position, said baseplate is
positioned sufficiently beneath the seat to permit at least on removable
battery unit to be accommodated between said baseplate and the seat, said
hinge assembly is in a first position and said first and said second
plates are longitudinally adjacent to each other, and wherein, when the
wheelchair is in the folded position and said removable battery unit is
removed, said hinge assembly is moved to a second position located
relatively above said first position and said first and said second plates
are moved to an angle relative to each other, approaching parallel
positions in longitudinal planes.
2. A foldable motor driven wheelchair according to claim 1 wherein said
second longitudinal edge of said first plate and said second longitudinal
edge of said second plate are in proximity to each other.
3. A foldable motor driven wheelchair comprising:
a first and a second side frame, parallel to each other and extending in
vertical and longitudinal directions;
a foldable seat carried by and extending transversely between the side
frames;
a supporting structure connecting the side frames for motion between an
unfolded position in which the side frames are spaced sufficiently apart
to accommodate an occupant with the seat unfolded thereunder and a folded
position in which the side frames are relatively closer together in
side-by-side relation with the seat folded therebetween;
a motor controller supported on at least one of said side frames;
at least one electric motor supported by at least one of the side frames
and electrically coupled to the motor controller;
a foldable baseplate pivotably connected to and extending between the
wheelchair side frames wherein said foldable baseplate includes a first
plate and a second plate movably connected to each other by a hinge
assembly having a pivot point and at least one first hinge member and at
least one second hinge member extending outward from said pivot point,
wherein said at least one first hinge member is attached to said first
plate and said at least one second hinge member is attached to said second
plate;
means of mechanically affixing said removable battery unit to said foldable
baseplate;
means attached to said foldable baseplate of electrically connecting said
removably battery unit to said motor controller;
further comprising means for selecting between manual and motor driven
propulsion of said wheelchair;
wherein said selecting means includes a handle pivotably mounted on a drive
hub which engages a wheel of said wheelchair to said electric motor for
motor driven operation and disengages said wheel for manual operation when
the handle is pivoted from one position to another and locking pins
coupled to said handle engage and disengage a hub of said wheel,
respectively; and
wherein, when the wheelchair is in the unfolded position, said baseplate is
positioned sufficiently beneath the seat to permit at least one removable
battery unit to be accommodated between said baseplate and the seat, said
hinge assembly is in a first position and said first and said second
plates are longitudinally adjacent to each other, and wherein, when the
wheelchair is in the folded position and said removable battery unit is
removed, said hinge assembly is moved to a second position located
relatively above said first position and said first and said second plates
are moved to an angle relative to each other, approaching parallel
positions in longitudinal planes.
Description
CROSS-REFERENCE TO RELATED APPLICATION
This application is being simultaneously filed with a commonly assigned
application Ser. No. 07/578,587 for "WHEELCHAIR DRIVE ASSEMBLY".
BACKGROUND OF THE INVENTION
Over a period of many years power wheelchairs have been developed to
increase the independence and mobility of handicapped people. While many
advances have been made in the development of power wheelchairs, many
problems remain. For example, insertion and removal of batteries is quite
difficult for a disabled person. Typically the batteries must be removed
from either the back or the side of a wheelchair. Frequently batteries
must be removed for transportation or service. The heavy battery terminal
wires must be removed before a battery is removed and then must be
reconnected when a new battery is inserted. The process for inserting and
removing the batteries may thus be quite difficult for a user of the
wheelchair who does not have the strength to lift the batteries or the
manual dexterity to easily make electrical connections by hand. The
electrical connection between the battery and the controller/motor of the
wheelchair also comprises an exposed wire which could loosen, corrode, or
snag while the wheelchair is in use, possibly disabling the wheelchair and
stranding the occupant.
The batteries are sufficiently heavy that they significantly affect the
center of gravity of a wheelchair. This is particularly true when the
batteries are located behind the seat. In order to provide adequate
stability, it has usually been necessary to move the rear wheels rearward
to a position behind the seat and thereby increase the length of the
wheelbase. This makes the wheels very difficult to reach for manual
propulsion of the wheelchair by an occupant. In addition, the rear drive
wheels for motor driven wheelchairs are made smaller than conventional
22-26 inch diameter wheelchair wheels. In addition to placing the rear
wheels out of the reach of the occupant, the larger wheelbase means that
the wheelchair is less maneuverable.
Even if the occupant could reach the rear wheels to self propel the
wheelchair, there would be no way for the occupant to disconnect the
wheels from the drive motors. Manual self-propulsion of a motorized
wheelchair by an occupant has thus been completely impractical.
Many examples of battery-powered wheelchairs may be found on the market.
One such battery-powered wheelchair is foldable and has two batteries
supported under the seat of the wheelchair on a foldable baseplate. The
two batteries of the wheelchair must be removed from the side of the
wheelchair and they must be removed together, that is, one of the
batteries cannot be removed by itself. Insertion and removal of the
batteries also requires that the wires which make the electrical
connection between the batteries and the motor must be connected by hand.
Furthermore, the rear wheels of the wheelchair are small and are not
designed for the occupant of the wheelchair to be able to reach out and
propel the wheelchair by hand when the motor is not energized. Thus, the
wheelchair can only be propelled by another person who must push the
wheelchair when the motor is not energized.
SUMMARY OF THE INVENTION
A foldable, portable motorized wheelchair in accordance with the invention
may be either power driven or manually propelled by the occupant. The
wheelchair includes opposed side frames supporting a seat having a back
support between them. Also secured to the side frames are a motor drive
system, a pair of rear wheels, a pair of castor mounted front wheels, a
pair of footrests and a folding battery support assembly that supports two
batteries beneath the seat with front access for removal and insertion of
batteries.
The rear wheels are implemented as large, 24 inch diameter wheels with a
center of rotation placed in front, under or behind the seat back support.
A hand ring is mounted on the outside of the rear wheels and a manually
operated quick release hub drive mechanism enables the wheelchair occupant
to selectively disengage the rear wheels from the motor drive system. The
wheelchair may thus be selectively operated as either a motorized battery
powered wheelchair or as a manually self-propelled wheelchair.
The folding baseplate assembly supports the required battery or batteries
beneath the seat and, when the batteries are removed, enables the
wheelchair to be folded to a laterally more compact condition. When
folded, the wheelchair may be stored or transported much like a
conventional nonpowered wheelchair.
The battery support assembly includes a folding baseplate and battery units
that are secured by slide rails to the baseplate. The support assembly
provides the wheelchair occupant with convenient access to the batteries
while mating slides and electrical connectors on the baseplate and battery
units enable battery units to be easily slid into or out of automatic
connection on the baseplate. All electrical connections are automatically
made or broken by the mating electrical connectors and no separate wiring
connections are required.
The quick release hub drive mechanism has a handle that is readily reached
by a wheelchair occupant and selectively engages or disengages the rear
wheels from the motors. Different, tactiley distinguishable surfaces are
provided on opposite sides of the engagement control handle. This enables
the wheelchair occupant to be able to detemine without visual observation
whether a hub drive mechanism is in the engaged or disengaged position.
BRIEF DESCRIPTION OF THE DRAWINGS
A better understanding of the invention may be had from a consideration of
the following Detailed Description, taken in conjunction with the
accompanying drawings in which:
FIG. 1 is a simplified perspective view of a selectively power driven or
occupant self propelled wheelchair in accordance with a preferred
embodiment of the invention;
FIG. 2 is a partly phantom perspective view of a battery support assembly
used in the wheelchair shown in FIG. 1;
FIG. 3 is a cross-sectional end view of the base of the battery support
assembly shown in FIG. 2 taken along lines 3--3;
FIG. 4 is a front view of a foldable base plate used in the support
assembly shown in FIG. 2, the baseplate assembly being shown in a folded
configuration;
FIG. 5 is a cross-sectional view of a pivotable bearing connection between
a wheelchair frame and the foldable baseplate shown in FIG. 4;
FIG. 6 is a perspective view of a wheelchair showing a releasable wheel
drive assembly in accordance with the invention;
FIG. 7 is an exploded perspective view of the releasable wheel drive
assembly in accordance with the invention;
FIG. 8 is a cross sectional view of the wheel drive assembly shown in FIG.
7 with locking pins in an engaged position;
FIG. 9 is a cross sectional view of the wheel drive assembly shown in FIG.
7 with locking pins in a disengaged position;
FIG. 10a is a front perspective view of a U-shaped toggle handle used in
the releasable wheel drive assembly shown in FIG. 7;
FIG. 10b is a rear perspective view of a U-shaped toggle handle used in the
releasable wheel drive assembly shown in FIG. 7; and
FIG. 11 is a simplified rear perspective view of a power driven wheelchair
in accordance with the invention with the battery support assembly removed
.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring now to FIG. 1, a foldable, selectively power driven or manually
self propelled wheelchair 10 in accordance with the invention includes
opposed right and left side frames 12, 14 providing the primary structural
support for wheelchair 10. A seat 16 having a back support 18 extends
between frames 12, 14 to support a wheelchair occupant (not shown). Also
supported by the frames 12, 14 are left and right rear wheels 20, 22, left
and right castor mounted front wheels 24, 26, left and right foot supports
28, 30, a motor drive system 32 and an energy supply system in the form of
a battery support assembly 34. The rear wheels 20, 22 are identically
mounted on a frame 10 by a selectively releasable hub drive mechanism 40
as illustratively shown for rear wheel 20.
The wheelchair side frames 12, 14 are made primarily of strong, lightweight
tubing of a metal such as aluminum or steel alloy. The side frames are
connected by a foldable supporting structure 42. The side frames 12, 14
include a pair of vertically extending members 44, 46 which support seat
back 18 between them and also support a pair of rearwardly extending
handles 48, 50. The side frames 12, 14 further include longitudinally
extending tubular members 52, 54 which support assembly 34. Front vertical
frame members 56, 58 extend upwardly from longitudinal frame members 52,
54. The seat 16 is either removable or foldable to allow the wheelchair 10
to be folded to a more laterally compact condition.
Referring now to FIGS. 2-5 the battery support assembly 34 includes a
foldable baseplate assembly 70 and energy supply units in the form of
battery units or batteries 72, 74. The foldable baseplate assembly 70
includes two coplanar support plates 78, 80 mounted in side-by-side
relationship with opposed, abutting edges 82, 84 extending in a
longitudinal direction. Plate 78 has a planar top surface 85 and a planar
bottom surface 85, while plate 80 has a planar top surface 87 and a planar
bottom surface 88.
Affixed to the bottom surfaces 86, 88 are a pair of longitudinally spaced
identical hinges 90 (only the front most hinge being visible in the
figures). The hinges 90 each have first and second hinge members 92, 94
which are pivotally jointed at a pivot point 96 in a conventional manner.
First hinge member 92A is secured by welding or other suitable means to
bottom surface 86 of plate 78 while a second hinge member 94 is secured to
bottom surface 88 of plate 80.
Plate 80 may be wider than plate 78 so that abutting edges 82, 84 meet at a
location distanced from the pivot point 96 and to the right thereof as
viewed looking rearward in FIGS. 1-4. As a result, the plates 78, 80 are
free to fold with the center pivot point 96 moving upward and the bottom
surfaces 86, 88 moving toward each end, facing relationship, moving toward
a parallel configuration. As the plates 78, 80 are unfolded and reach a
side-by-side coplanar relationship, the hinge member 92 comes into
engagement with bottom surface 88 of plate 80 and serves as a stop to
prevent further unfolding of plates 78, 80. A stable firm flat battery
support base is thus formed by plates 78, 80 when they are unfolded to
their coplanar relationship.
Two longitudinally extending pairs of rails 102, 104 and 106, 108 are
secured to the top surface 85, 87 of plates 78, 80 by screws 110, welding
or other suitable means. The hinges 90 and hinge members 92, 90 operate as
braces to help strengthen the support plates 78, 80. The plates can thus
be made of thinner, lighter material and can have material removed at a
central region to further reduce weight. Each rail includes a vertically
extending bar portion 112 and a horizontally extending bar portion 114
which is cantilevered atop the vertical bar portion 112 and extends
horizontally inward toward the other rail of the pair to form an inverted
L-shape. The outer rails 102, 108 are positioned approximately 3/8 inch
longitudinally farther forward than the inner rails 104, 106. This
simplified the insertion of battery units 72, 74 by allowing the outer
rails 102, 108 to first be aligned, with the inner rails 104, 106
subsequently being aligned. The front edges 116 of horizontal bar members
114 are chamfered to further facilitate alignment of a battery unit 72 or
74 with the rails during insertion.
A pair of drive system electrical connectors 118, 120 are secured to the
top surfaces 85, 87 proximate the pairs of rails 112, 114 and 116, 118.
More particularly the connectors 118, 120 are secured midway between the
respective pairs of rails 102, 104 and 106, 108 with a longitudinal
position rearward of the halfway position. The connectors 118, 120 couple
electrical power to the motor drive system 32. A spacer bar 122 and spacer
washer 124 provide proper height adjustment of connector 118 above surface
82.
The electrical connectors 118, 120 each have two internal flat planar
contacts 126, 128. The contacts 126, 128 are secured at the rear thereof
to the body of the connector as well as to wires 180 and extend
longitudinally forward to enable secure engagement with mating contacts on
the battery units 72, 74.
Two pairs of pivot bearings 132, 134 and 136, 138 are welded to the
opposite lateral extremities of the plates 78, 80, distanced from edges
82, 84 to pivotally secure the baseplate assembly to the sideframe
longitudinally extending members 52, 54. The wheelchair 10 can thus be
folded to a laterally more compact condition. With the battery units 72,
74 removed, the abutting edges 82, 84 can rise as they pivot about pivot
point 96 of hinge 90.
As representatively illustrated in FIG. 5 for pivot bearing 136, each of
the pivot bearings 132, 134, 136, 138 is generally cylindrical in shape
and has two end regions with internal enlarged bores 150, 152. Bores 150,
152 receive low friction plastic bearing inserts 154, 156 to prevent
binding as the pivot bearing 136 is rotated relative to longitudinal side
frame member 54. A small gap (not shown) in the circumference of
cylindrical inserts 154, 156 enable them to be positioned at the enlarged
bores 150, 152 and then expanded to mate therewith.
The battery units 72, 74 may be identical and, as represented by unit 74,
include a bottom plate 160 supporting a battery housing 162 having a
container portion 164 and a lid portion 166. A strap 168 forms a first
loop as it extends from between bottom plate 160 and housing 162 at the
left front of the battery unit 74 to a fastener 170 on a front wall of
container 164. A second, larger loop is formed as strap 168 extends from
fastener 170 diagonally over the top of battery unit 74 to securement
between housing 162 and bottom plate 160 at the lower right rear of
housing 162 (as viewed in FIG. 3). The first loop thus provides a
convenient handle for sliding battery unit 74 in and out of position on
support plate 80 while the second loop provides a convenient carrying
handle. A battery 180 having positive and negative terminals 182, 184 is
disposed within housing 162.
Battery unit 74 further includes a pair of longitudinally extending
L-shaped rails 190, 192 secured to a bottom surface of bottom plate 160.
Rails 190, 192 each have a vertical bar 194 extending downward from the
bottom of plate 160 and a cantilevered horizontally extending bar 196
which extends horizontally outward away from the rail in the pair 190, 192
a short distance.
The rails 190, 192 are laterally spaced to fit just inside of a pair of
rails 102, 104 or 106, 108 to form a secured, longitudinally slidable
mating relationship with rail 106, 108 on support plate 80, as seen in
FIG. 3. Horizontal bar 196 slides beneath horizontal bar 114 to assure
that battery unit 74 is securely retained in place on support plate 80.
The rails 190, 192 and 116, 118 thus form a slide assembly having mating
pairs of slides that provide convenient insertion and removal of the
battery units 74 with access through the front of the wheelchair 10.
A cross plate 200 is longitudinally positioned approximately midway along
rails 190, 192 at a pair of recesses 202, 204 and extends laterally
between the rails 190, 192. Cross plate 200 supports a two contact battery
side electrical connector 210 which is shaped to matingly engage and make
electrical contact with the drive system electrical connectors 118, 120.
Connector 210 also connects with a wire set 212 (see FIG. 2) which passes
through a hole 214 in bottom plate 160 to provide electrical connection to
battery terminals 182, 184. Battery unit 74 may thus be removed from or
inserted into wheelchair 10 with no need to make a separate connection to
the battery terminals 182, 184. Electrical connector 210 remains connected
to the terminals and as it mates with connector 120 during insertion a
full electrical circuit is automatically completed from battery 180 to
controller/motor drive system 32. The need for the wheelchair occupant or
other person to deal with the battery connections upon inserting or
removing a battery unit 72, 74 is eliminated.
In addition to being laterally foldable in a manner similar to a
conventional nonmotorized wheelchair, foldable wheelchair 10 can
selectively be operated in a motorized mode or in a manual propelled mode.
An assistant can of course use handles 48, 50 to propel wheelchair 10 from
the rear as well.
Making reference now to FIGS. 6-11, the motor drive system 32 includes a
manual joy stick controller 222 receiving energy from an energy supply
system and two motors 226, 228 (see, for example, FIG. 11) independently
driving the rear wheels 20, 22 in response to manipulation of the joy
stick controller 222.
The front wheels 24, 26 are castor mounted and have no independent steering
capability. They are passively responsive to the steering motion of the
wheelchair 10. Steering may thus be completely controlled through the
independent motion of rear wheels 20, 22.
Occupant manual propulsion of wheelchair 10 is enabled by providing large,
24 inch diameter rear wheels 20, 22 by providing a center of rotation for
wheels 20, 22 at, in front, under or behind the seat back support 18, by
mounting a manual propulsion or drive ring 230 on the outside of wheels
20, 22 and by coupling the wheels 20, 22 to their respective drive motors
226, 228 through a manually releasable hub assembly 300. When hub assembly
300 is disengaged the associated rear wheel 20, 22 of wheelchair 10 is
completely disconnected from drive motors 226, 228.
A separate hub assembly 300 connects each drive motor 226, 228 to its
associated rear wheel 20, 22 respectively. Thus, while only the hub
assembly 300 coupling motor 226 to rear wheel 20 is illustrated and
described in detail, it will be appreciated that a substantially identical
hub assembly connects drive motor 228 to rear wheel 22.
As seen, for example, in FIG. 7, hub assembly 300 includes a drive axle 312
having an inner driven end permanently coupled through an axially
extending worm gear assembly 314 to motor 226 which has an axis of
rotation extending parallel to drive axle 312. While most of drive axle
312 is cylindrical in shape, an opposite, free end 316 of drive axle 312
has a square shape and is received in mating relationship by an axially or
laterally extending square aperture 318 in a generally cylindrical drive
hub 320. This condition is best seen in FIGS. 8 and 9. The square shapes
of end 316 and aperture 318 serve as a key to prevent relative rotation
between shaft 312 and drive hub 320. A bolt 328 secures drive hub 320 to
free end 316 of drive axle 312.
Worm gear assembly 314 and correspondingly shaft 312 carried thereby are
mounted by bolts 322 to a metal plate 324 which forms part of side frame
14 and is positioned longitudinally in front of vertical member 44, which
supports seat back support 18. Drive axle 312 receives and rotationally
supports a central hub 326 of rear wheel 20 laterally outside of side
frame 14. The central axis 330 about which wheel 20 rotates is thus
positioned longitudinally forward of seat back support 18. In this
position a wheelchair occupant can conveniently reach the center of wheels
20, 22 to toggle releasable hub assembly 300 between states of engagement
and disengagement. The occupant can also conveniently reach the hand rail
230 to manually self propel and guide wheelchair 10.
In addition to drive hub 320 the other elements of releasable hub assembly
300 include a spider 336 which engages central hub 326, a pair of locking
pins 338, 340, a pair of springs 342, 344, a toggle handle 346, and a pair
of pivot pins 348, 350 for pivotally securing handle 346 to the locking
pins 338, 340.
Central hub 326 is preferably made of plastic and has a cylindrical center
hub 352 that is connected by multiple radial spokes 354 to a cylindrical
middle hub 356. Bearings 358 rotationally mount center hub 352 and hence
wheel 20 on drive axle 312,
Spider 326 is a generally cup-shaped member having a generally cylindrical
sidewall 360 and a disk-shaped end wall 362 affixed thereto. Sidewall 360
has multiple axial slots 364 which mate with spokes 354 as spider 326 is
slid into engagement with central hub 326. The engagement between spokes
354 and slots 364 precludes relative rotation between spider 336 and
central hub 326 of wheel 20.
The end wall 362 of spider 336 has a large central bore 370 that
concentrically mounts over center hub 352 and receives drive axle 312 and
multiple axially extending, circumferentially spaced, diametrically
opposed pairs of locking pin holes 372 distributed at equal radii about
central axis 330. Spider 336 is made of metal with hardened bushings
forming locking pin receptacles 372 that can receive locking pins 338, 340
without sustaining damage that might be inflicted if locking pins 338, 340
were allowed to directly engage the plastic central hub 326.
Drive hub 320 is a generally cylindrical member having a laterally outward
facing circular end surface 374 having a rectangular shaped slot or groove
376 defined therein to a depth of about 154 inch. A pair of locking pin
bores 378, 380 extend axially through drive hub 320 at radial positions
matching the radial positions of locking pin bores 372 in spider 336.
Bores 378, 380 each have a large diameter section 382 that mates with and
guides the large diameter laterally inward locking end 384 of locking pins
338, 340 and a small diameter section 386 that matingly receives a small
diameter shank portion 388 of locking pins 338, 340. The springs 342, 344
are inserted in the bores 380, 378 ahead of locking pins 338, 340 and thus
tend to force locking pins 348, 350 laterally inward toward spider 336.
Handle 346 is a generally U-shaped member having a cross bar 394 with two
oppositely positioned, parallel side bars 396, 398 extending therefrom.
The side bars 396, 398 terminate in ends 400, 402 having slots 404, 406
adapted to receive the outward ends of shank portions 388 of respective
locking pins 338, 340.
A pair of transverse bores 410, 412 pass through the ends 400, 402 of side
bars 396, 398 in a direction parallel to cross bar 394. Handle 346 has
first and second opposed parallel planar side surfaces 416, 418. Bores
410, 412 are located eccentrically with respect to these side surfaces
416, 418 and also with respect to ends 400 402 to enable the axial
positioning of locking pins 338, 340.
The shanks 388 of locking pins 338, 340 are sufficiently long relative to
the depth of a large diameter section 382 of bores 378, 380 and the
thickness of drive hub 320 that they may be forced laterally outward to a
position wherein transverse pivot pin bores 422, 424 located near the ends
thereof extend beyond the outer surface of drive hub 320. From this
position the ends 400, 402 of handle 346 can be joined with the shank ends
of locking pins 348, 350 with the ends being received into slots 404, 406
such that bores 422, 424 may be axially aligned with the bores 410, 412 in
handle 346. With the bores thus aligned pivot pin 348 may be inserted into
bores 422 and 410 to pivotally attach locking pin 338 to handle side
member 396 and pivot pin 350 may be inserted into bores 424 and 412 to
pivotally attach locking pin 340 to hand side member 398. With the locking
pins 338, 340 thus attached to handle 346 they may be released to allow
springs 342, 344 to force handle ends 400, 402 axially inwardly into
rectangular groove 376. The sidewalls of groove 376 then serve to restrain
pivot pins 348, 350 to maintain the assembled arrangement.
The bores 410, 412 are eccentrically located closer to second surface 418
than first surface 416 and closer to first surface 416 than to ends 400,
402. Handle 346 may thus be toggled by rotation between two stable
positions 180 degrees apart. The two surfaces 416, 418 are made tactilely
distinguishable by roughening surface 416 at area 428, by defining letters
in one of the surfaces or by means of some other technique which allows a
wheelchair occupant to determine the toggle state of handle 346 simply by
touching the handle surface and without visual inspection. The occupant
may thus be able to readily determine whether or not the rear wheel hubs
are engaged or disengaged.
When handle 346 is rotated to the position wherein first surface 416 faces
outward as shown in FIG. 8, the locking pins 338, 340 are released so as
to be forced by springs 342, 344 toward the spider 336. When the wheels
are rotated so that the pins 338, 340 become aligned with a pair of
locking pin bores 372 the pins move axially inward to enter the bore 372
and rotationally lock the rear wheel 20 or 22 to drive hub 320 and hence
to drive system 32. In this position the occupant can feel the roughened
area 428 to confirm the engaged condition.
When handle 346 is toggled 180 degrees to the engagement stable condition
as shown in FIG. 9, the locking pins 338, 340 are lifted from the bores
372 in spider 320 to allow rear wheel 20 to turn freely relative to drive
hub 320. In this position, the wheel chair occupant can feel the smooth
side 418 of handle 346. Wheelchair 10 can be manually guided and propelled
without encountering any drag from the drive motors 226, 228.
While there has been shown and described above a particular arrangement of
a foldable, selectively motor driven or self propelled wheelchair in
accordance with the invention for the purpose of enabling a person of
ordinary skill in the art to make and use the invention, it will be
appreciated that the invention is not limited thereto. Accordingly, any
modifications, variations or equivalent arrangements within the scope of
the attached claims should be considered to be within the scope of the
invention.
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